2 Outline Formation and detection of molecules Cooling to condensationCondensatesDouble structureComparaison with other molecular condensatesSome more proofs of condensationCondensates in very anisotropic trapsAn ellipticity study

3 How to form molecules ? Sympathetic cooling of fermions byevaporation of bosonsTransfer into the optical trapHyperfine transfer by RF adiabatic passageIncrease of the magnetic field to 1060 GaussMixture: ½ Zeeman Transfer by RF sweep on resonance(Evaporation by lowering the trap intensity)Slow crossing of the Feshbach resonance(Further evaporation)Detection

4 How to detect dimer formation ?1,324For the probe laser to be on resonance, the magnetic field needs to be turned off. The unbrocken dimers are not detected.Double ramp method :a>0a<0Importance of the ramp speedAdiabaticity:Ancienne figure

5 Temperature effects The cooler, the more molecules,Independant of ramp speedThe molecules are likely to be in thermal and chemical equilibrium with the atomsCreating molecules is heating

7 How to directly detect molecules ?Low binding energy: It is possible to brake the molecules with a fast magnetic field sweepWhen breaking the molecules, some extra energy is releasedHigh field imagingRF dissociation of molecules during TOFDetection of molecules onlyIncrease B during TOF before breaking molecules while going to B=0Detection at low fieldCompensationcoils offOptical trap off0.2 ms0.2 ms0.8 msPinchcoils off

17 Conclusions Careful check of the number of remaining atomsLifetime of the condensateStudy of the value of TcEvaporation toward a pure condensateDecrease B to lower value, (decrease |a|)Coming back to the Fermion sideEllipticity as a function of degeneracy (a new thermometer)BCS …

18 High field imaging Which transition are we using ?The detuning is of the order of MHz in the region of interest.A double pass AOM at 225 MHz is added on the probe beam.1.5 10^5atomes